CarPC link above seems to be closest to actual, but most of the calculators underestimate RAM wattage. Compare to PC Power & Cooling's old estimate of 8w per 128MB and you can imagine this could cause some problems. They are easily the most respected PSU manufacturer, because of their powerful, honestly rated power supplies.

Of course, they want to sell you wattage, so do your own test. Try holding onto your RAM for 5 seconds after using it for awhile and tell me it is only putting out 7-10w...

It may not pay in money to be conservative in system power estimation, but it will certainly pay in time.

I could never see the whole eXtreme PSU Calculator CPU list because their text was so large it blocked the wattages so I hacked it a little and got the text file and then tediously seperated all the CPU's. You can then choose the CPU you want in their program and it will show the speed and voltage. Then you can click the overclock option and downclock or undervolt the CPU to see the new lower wattage. Pretty cool. As eXtreme updates the list, I will try to also. My list is from Dec.
Here is the list:

Update: It doesn't look like the wattages are displayed next to the processors any more. Use my list to see that info.

Also keep in mind that AMD list's the max wattage and Intel lists the "typical" or average wattage. Even then AMD's spec'ed max is usually higher than the chip really is. So expect the AMP to be a little less than what is rated and Intel to be a little higher than rated. This is just based on a lot of tests I've read and is pretty general. The bottom line is that AMD and Intel don't really want people to know the actual wattages.